OK, this has to count as one of the more annoying levels, because you have to try to follow the little blue glowing ball through it. It's one that's much easier once you play it a few times and know WHERE he is going to lead you, and just go there without actually having to wait for him.

While it might seem easier to try to outrun the enemies, it rarely works. It just means that when they all catch up with you there is a MASSIVE force to squash you. Also, you don't checkpoint until they all die, so when you DO die, you start at the beginning again. It's far better to go slowly, take out the enemies as you go, and pick up the weapons they drop.

OK, so head straight. Stop when you see red appear and take out the new group. You'll get a shotgun and ammo and such. At the end of the first room head right into the tunnel.

In the next room (with the big pit in the middle) head left to the tunnel entrance. Again, kill the monsters in here before stepping into the tunnel. A monster will drop right down on the other side of the tunnel, so once you 'trigger' him attacking, toss in a grenade or two to kill them off.

Move in and left to a big door. The blue ball will say it's locked and go off to unlock it. Meanwhile of course you're swarmed with monsters. Kill them off and gather up any weapons and ammo. Now he opens the door.

Head straight in to the glowing blue windows. Yup, more monsters. Go back and forth in front of the blue area until they're dead. Then go up the other side. There's an overshield down in one of the 'ditches'. Floating zappers will come to help out - hide until they're done so you're not zapped in the crossfire. There will be lots of ammo and such for you to grab.